If
∣
x
∣
2
+
∣
x
∣
−
6
=
0
,
then which of the fowling option is true?
(A) Product of roots is − 6
(B) Sum of the roots is + 1 or − 1
(C) Both (A) and (B)
(D) None of these.
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Well actually there are also infinitely many complex roots, e.g. x = ± 2 i , x = ( 1 ± i ) 2 , etc.
Edit: the general solution is − 2 ≤ Re ( x ) ≤ 2 , Im ( x ) = ± 4 − ( Re ( x ) ) 2 It is a circle of radius 2 centered about the origin in the complex plane. So the product is divergent and the sum is 0 .
or just observing the coefficents
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Sorry, what?
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vieta formula
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@Mardokay Mosazghi – hmm...we are having extraneous roots, will vieta work?
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@Soumo Mukherjee – i agree i guess it was just an observation btw nice solution sir
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@Soumo Mukherjee – ok bro but sir is a term used for respect
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Note: ∣ x ∣ isn't the variable. x is the variable.
∣ x ∣ 2 + ∣ x ∣ − 6 = 0 ⇒ ( ∣ x ∣ + 3 ) ( ∣ x ∣ − 2 ) = 0 .
But, ∣ x ∣ + 3 = 0 because ∣ x ∣ = − 3 (i.e ∣ x ∣ cannot be negative.)
Therefore, ∣ x ∣ − 2 = 0 ⇒ x = 2 o r − 2 . .
Clearly sum of roots is 2 + ( − 2 ) = 0 and product of roots is 2 × ( − 2 ) = − 4 . None of which are given in the options.
Hence the answer is (D) None of these ''.